Process for making helically wrapped insulation

ABSTRACT

A process for producing a helical laminated tape preferably having at least one strip overlappingly superimposed on another strip of about the same width, including the step of dusting any remaining exposed area of the overlapped tape before forming adjacent coils, whereby subsequently formed adjacent coils do not become bonded during a subsequent cure, thereby resulting in a stepped and tiered tape having overlapping edges for enhanced heat and fire protection, and being easily uncoiled from or subsequently recoilable on any desired cylindrical or tubular mounting means.

llnited States Patent Reynolds, Jr.

[151 3,657,041 [4 1 Apr. 18, 1972 [54] PROCESS FOR MAKING HELICALLY WRAPPED INSULATION [72] Inventor: Harold J. Reynolds, Jr., Raritan, NJ.

[73] Assignee: Johns-Manville Corporation, New York,

[22] Filed: Jan. 5, 1971 [21] Appl. No.: 103,970

Related US. Application Data [62] Division of Ser. No. 768,398, Oct. 17, 1968, abandoned.

[52] U.S.Cl ..156/190, 156/195, 156/276, 156/289, 156/301 [51] Int. Cl ..B65h 81/04 [58] Field ofSearch ..156/190, 191, 195, 289, 276, 156/301, 184, 192

[56] References Cited UNITED STATES PATENTS 2,266,226 12/1941 Mall ..156/190 2,539,450 l/l95l Magill ..l56/289 X 3,202,560 8/1965 Michael ..l56/289 X 3,271,221 9/1966 Sheehan 156/190 3,367,816 2/1968 Mills et al. 156/190 3,489,636 l/l970 Wilson ....l56/289 X 3,531,350 9/1970 Rausing et a1 156/289 X Primary Examiner-Leland A. Sebastian Assistant Examiner-Gary G. Solyst Attorney-John A. McKinney and Robert M. Krone ABSTRACT A process for producing a helical laminated tape preferably having at least one strip overlappingly superimposed on another strip of about the same width, including the step of dusting any remaining exposed area of the overlapped tape before forming adjacent coils, whereby subsequently formed adjacent coils do not become bonded during a subsequent cure, thereby resulting in a stepped and tiered tape having overlapping edges for enhanced heat and fire protection, and being easily uncoiled from or subsequently recoilable on any desired cylindrical or tubular mounting means.

4 Claims, 10 Drawing Figures DRIVING MECHANISM PATENTEDAPR 18 IQTE 3, 657, 041

sum 1 GF 3 DRIVING MECHANISM HAROLD r! Raw/01.05, r/R.

PATENTEDAPR 18 1972 3. 657, 041

SHEET 3 BF 3 INVE/V TOR HAROLD cl. fi'yalows, c/.

CROSS-REFERENCE TO RELATED APPLICATION This is a division of application Ser. No. 768,398 filed Oct. 17, 1968 now abandoned.

BACKGROUND OF THE INVENTION This invention is directed to a helical tape for providing heat protection to typically cylindrical means in need of such protection, which tape is further characterized by being easily uncoiled for purposes of necessary inspections and/or repairs of the cylindrical means, and subsequently as easily recoiled to reestablish the original fire and heat protection. Also the invention is directed to a process for making such a tape having a composition of one or more possibilities, a particular tape having a novel composition, and an apparatus employable in the above process.

Although by a different process such as that disclosed in copending US. Pat. application Ser. No. 701,424, commonly assigned, of which the Applicant is a co-inventor, it is possible to produce either rubber or silicone tape generally of the same construction as the subject matter of this invention, it is not possible to satisfactorily produce such a tape when the diameter of each helical turn (coil) is of a diameter of about one-half inch or less, when concurrently at least one of the strips being laminated is a silicone coated strip, because the rollers necessary in that process slip on the surface of the silicone thereby interfering with a proper feed of the silicone-coated or silicone-impregnated tape.

However, because of the high utility of silicone in offering protection against either or both heat and flame, it is desirable to have a method for producing helical tape having a coil diameter of about one-half inch or less.

Additionally, it is desirable to have a process which may be employed interchangeably either with the use of silicone-impregnated strips of random diameters of the helix, or with the usual rubber impregnated strips for the production of the helical strips, rather than having to employ one process and apparatus for the production of one and a second separate process and apparatus for the production of the other.

As discussed in the above referred to application Ser. No. 701,424, when helical tapes having a utility of tire protection are employed in and around gas line or other critical areas, it is desirable that the fire-protective coverings of such lines be easily removable and thereafter easily replaceable in order to facilitate necessary periodic inspections of such gas lines or other parts being protected. Such a procedure of repeated inspections requiring repeated removals and replacement, requires the fire-protective tape to have both sufficient resiliency and elasticity that the tape remains firmly and snugly in place except when removed, and when removed that it nevertheless springs back readily to its helical form. It desirably is easily thereafter rewindable on the typically cylindrical object being protected from heat or fire to form again a snug protective removable cover on the cylindrical form, for example. Such a tape having these desired characteristics must of necessity include a good bond between the separate strips previously laminated to produce the tape of the type to which this invention is directed; otherwise, separate strips during repeated removal and replacement of the tape eventually would become separated to impair the fire protection and also to impair the utility of the tape for replacement (reuse) after the inspection. Accordingly, for a silicone-coated asbestos cloth, for example an improved bond resulting from the cure of the laminate is desirable, the alkalinity of the asbestos cloth prior to this invention interfering with and degrading the quality of the bond between laminated strips where at least one of the strips is an asbestos cloth coated or impregnated with the silicone.

In order to overcome each and every one of these diverse problems, it became necessary to discover an entirely new process and apparatus for producing the tape of this invention.

THE OBJECTS Accordingly, an object of this invention is a process for producing a laminated and stepped tape including at least one strip, as a strip-layer of the laminate, of silicone-coated material in which the silicone composition thereof produces an improved bond when cured in laminate form with another similar or dissimilar strip.

Another object is a process for producing a helical laminated and stepped silicone tape having at least one silicone strip, in which the diameter of the coils thereof ranges up to about 0.5 inch.

Another object is a process for producing a helical stepped and laminated tape having at least one silicone coated or impregnated asbestos cloth and the laminated helical tape formed thereby, using a particular catalyst.

Another object is a process for producing a stepped and laminated helical tape of any desirable composition and having any desirable diameter, thereby not requiring separate processes and apparatus for the production of different types of stepped and laminated tape.

Another object is an apparatus for practicing the above desired processes.

Another object is a helical stepped and laminated tape having at least one strip of the laminate of a silicone-coated or impregnated type, and having a diameter ranging up to about 0.5 inches.

Another object of this invention is a helical stepped and laminated tape having at least one strip of the laminate composed of a silicone-coated or impregnated asbestos cloth with a high degree of bond between the laminated strips, in which the silicone is selected from a particular group.

Other objects of this invention become apparent from the preceding and following disclosure.

SUMMARY OF THE INVENTION The above objects are obtained by a particular process of making a stepped and laminated helical tape in which a plurality of strips having an adhesive coating thereon are superimposed on one-another in a manner whereby the superimposed strips at least slightly overlap a lower tape on which the particular overlapping strip is superimposed, and in which the superimposed strip and the overlapped strip have a substantially parallel alignment in the form of a laminated coil wrapped around a mandrel, the novelty and improvement in this process comprising (1) the application of a composition which substantially overcomes and neutralizes any tackiness on the remaining top surface of the overlapped strip before" forming a following adjacent coil, for example preferably after the superimposed strip is superimposed upon the overlapped strip, whereby the portion of the superimposed strip extending beyond the edge of the overlapped strip does not substantially adhere to the remaining exposed area of the overlapped strip of the adjacent coil subsequently formed, i.e., adjacent strip wrapped around the body of the mandrel, for example, and (2) the requirement that all strips of tape have about the same width, which must be at least less than the circumference of the mandrel. In the absence of a neutralizing composition of this type, such as a talc or other dusting composition to counteract tackiness, for example, thereafter upon the wrapping of the strips in the formation of subsequent turns of coils of the helical strips, each exposed area of overlapped strips would adhere to the preceding turn of the overlapping strip, resulting in the formation of a solid cylinder which after curing would be firmly set and would not be in the form of a laminated and stepped tape, much less an uncoilable tape.

Accordingly, for any process of helically wrapping a plurality of superimposed adhesive-treated fibrous strips, such as silicone-treated asbestos strips, in overlapping and substantially parallel alignment on a mandrel means sufficiently to form helical, laminated coils of multiple strip thickness, and thereafter curing the wrapped strips, the improvement of this invention comprises applying to all substantially remaining exposed areas of each overlapped face of said strips, a composition such as a dusting powder substantially neutralizing any tackiness of an adhesive of said areas, said applying being prior to wrapping an adjacent and overlapping coils, for each successively wrapped coil of said plurality of strips, whereby said helical, laminated coil is uncoilable into a spiral, stepped, and laminated tape, and recoilable into an integrated heat and fire protective covering.

By the employment of this process, for the first time it is now possible to make such a tape having at least one strip thereof a silicone impregnated strip, and in which the helical laminated tape formed therefrom has a coil diameter ranging up to about 0.5 inch, i.e. it now being possible to have diameters of about 0.5 inch or less.

In another embodiment of the invention, the invention also includes the employment in particular of a silicone which includes an aliphatic or aromatic group having an unsaturated bond, such as a member selected from the group consisting of a vinyl group, a vinylidene group, a vinylene group, and a phenolic group such as a phenyl group, and which includes as a part of the silicone composition a curing catalyst selected from the group consisting of 2,5(Bis(ter-butyl-peroxy)-2-5 dimethylhexane and dicumyl peroxide, when at least one of the strips is an asbestos-coated strip, whereby an improved bond results upon curing of the laminate. The vinyl group is preferred.

In the apparatus of this invention for producing a tape of this invention by the above described processes of this invention, the improvement comprises a means for applying the neutralizing composition, such as a dusting box, located at a position at least prior in the process to the means for formation of the second and each subsequent adjacent coil in order to prevent the adhering of the consecutive laminated coils one to another.

BROAD DESCRIPTION In a preferred embodiment of this invention, at least one or more of the strips coated with an adhesive composition is an asbestos cloth fibrous material.

In another preferred embodiment of this invention, the adhesive composition coating the plurality of two or more strips is an elastomer composition.

In another preferred embodiment of this invention, the elastomer composition is a silicone composition, for at least one of the strips.

In another preferred embodiment of this invention, the silicone composition includes a silicone having a substituent thereon selected from the group consisting of a vinyl group and a phenyl group, at least one asbestos strip coated with the silicone, and a curing catalyst selected from the group consisting of 2,5(Bis(ter-butyl-peroxy)-2-5 dimethylhexane and dicumyl peroxide.

In another preferred embodiment, the diameter of the coils of the helical laminate-stepped tape in which at least one of the strips of the tape is a silicone coated strip, has a diameter of about one-half inch or less, i.e. a diameter ranging up to about 0.5 inch.

In another preferred embodiment of this invention, the neutralizing composition such as a dusting powder to substantially eliminate any tackiness of remaining exposed area of the face of an overlapped face of the strip, is applied after a superimposed strip has been superimposed and overlapped on the strip being overlapped, and as noted above prior to the formation of subsequent turns of the tape.

In another preferred embodiment of this invention, the dusting composition, or other equivalent neutralizing composition to overcome (counteract) the tackiness, is applied solely to the remaining exposed area of the overlapped face of the strip making up the part of the laminate.

In another preferred embodiment of this invention, separate guides are employed per strip to direct a first strip toward a mandrel to contact a surface of the mandrel around which the first strip is wrapped thereafter prior to and below the point of contact of a subsequent strip to be overlapped and superimposed upon the first strip which by similarly a first guide is directed to contact the mandrel in the overlapped portion of the overlapped strip at a point above the contact point of the first strip, whereby the first strip is already partially wrapped around the mandrel when the overlapping strip is superimposed upon the first strip. A second guide, per strip, regulates the angle of the direction of feed of each respective strip in relation to the acute angle between the strip being fed and the axis of the mandrel, and for subsequent strips regulates the angle between the feed of consecutive strips to one another. As in prior art processes directed to the forming of fused" helical coverings by the employment of separate strips wrapped on a mandrel typically in the manner described above, the angle between the direction of feed of any one or more strips and the axis of the mandrel is dependent upon initially, for the first strip, the diameter of the mandrel and the width of the strip, and for subsequently superimposed strips is dependent upon both the thickness of the overlapped strip and the diameter of the mandrel in conjunction, as well as the width of the strip being superimposed.

The invention is typically illustrated in the FIGS. I through IV.

FIGS. I through IV illustrate various embodiments of the process and apparatus of this invention whereby the tape is directed at desired and necessary angles to the mandrel around which they are wrapped in an overlapping relationship.

FIG. I (A) illustrates three separate feed rolls for three separate strips of tape in which each of the feed rolls and strips are directed from separate angles toward the mandrel through optionally tensioning means and through a guide per tape en route to the mandrel. Also a typical means for applying a neutralizing composition such as a dust box designated by x is illustrated as applying the dust or other equivalent composition to the remaining exposed areas of the overlapped strips of the laminated tape.

FIG. I (B) illustrates the same as I (A), except as shown from the left of top view, the FIG. I (A) illustrating a top view.

The FIG. I (C) illustrates the same as (A) and (B) except that (C) illustrates the apparatus as seen from a side view.

FIGS. II (A), (B), and (C) each illustrate a second embodiment basically similar to the embodiment of FIG. I, except that in FIG. II embodiments as illustrated in (A), (B), and (C), the rolls are on a common axis, for example, whereby the direction of feed from each of the rolls is parallel with two separate guides per strip, a first guide being to regulate the elevation of one strip relative to the other strip, and the second guide per strip being to regulate the angle of feed toward the mandrel relative to the axis of the mandrel.

FIG. III illustrates a preferred embodiment in which the feed rolls (not shown) are parallel initially in a manner such as illustrated in FIG. II, but in which the first guides of each of the strips, respectively, have an overlapping relationship to one another, the FIG. III being a view from behind feed rolls, facing the mandrel for movement along the axis of the mandrel from left to right.

FIGS. IV (A) and (B) illustrate the typical appearance of an uncoiled tape produced by the process and apparatus of this invention.

FIG. IV (C) illustrates a typical cross-section of the wound" and mounted helical, laminated and stepped tape of this invention.

In each of FIGS. I (A), (B), and (C), an embodiment of the process and apparatus of this invention are illustrated showing three separate views, view (A) being a top view as looking down upon three tapes separately mounted at different angles relative to the axis of the mandrel, to feed at the different angles respective strips of tape along their respective alignments which intersect before contacting the surface of the mandrel whereby each consecutive strip subsequently contacting the surface of the mandrel overlaps a portion of the width of a previously applied strip or the first applied strip, whereby half of each overlapped strip has about half of the width of an overlapping strip superimposed thereon in a manner whereby the overlapped strips have a substantially parallel alignment in the formation of the laminated and stepped tape.

It is immaterial in regard to the practice of this invention whether or not the mandrel is a revolving mandrel with the strips being fed from stationary feeding means or alternatively whether the feeding means (for the strips) revolve(s) around a stationary mandrel. In any event, one moves relative to the other in a manner whereby the strips are wrapped in a manner described above around the surface of the mandrel while simultaneously the feeding means or the mandrel itself move axially in relation to the other, whereby the consecutive coils being wrapped around the mandrel result in a helical coil having stepped coils slightly superimposed on and overlapping and adjacent coil at one edge and being overlapped on the op posite edge.

Accordingly, as the two or more strips of tape, three in the case of FIG. I, initially make contact with the surface of the mandrel, they must in one manner or another be sufficiently secured to the mandrel as to avoid slippage or unravelling and as to make possible the holding fast thereof while the first coil is wrapped around the mandrel.

In FIG. I, three separate feed strips of tape directed in at separate angles are identified by strip d, strip e, and strip f as each respectively is fed through its respective optional tensioning means collectively designated g, through each respective tapes guide rolls designated a, b, and c. Tape d is the first tape to contact the mandrel and is wrapped directly on the mandrel.

In initially setting up the tapes in the apparatus for practicing the process of this invention, the tapes may be secured by any convenient means to the mandrel. Also, the strips of tape may be either l) pinned collectively to the mandrel, without regard to the overlapping relationship, relying on the apparatus guides to promptly establish the desired and/or predetermined stepped and overlapping relationship when wrapping begins, or (2) pinned in the correct stepped and overlapping relationship whereby initially an entire face of strip d and half-a-face width of each of tapes e and f touch the mandrel. After completion of a first coil on a mandrel, when the stepped and laminated helical tape is in a ship-lap joint relationship, regarding the edges of the tape to one another for adjacent coils, the inner laminated strip d always has one full inner face in contact with the mandrel, the strip e always has up to preferably about one-half of the width of one face superimposed upon and laminated to up to preferably about one-half of the width of the outer face of strip d of the same turn, the remainder of the same inner face of strip e of the same turn overlapping the exposed remainder. of the upper face of an adjacent coil strip d, and the remainder of the strip e width on the outer face, of the same turn, being laminated with a superimposed about one-half-width inner face of laminated strip f. Accordingly, the helical stepped tape of this invention, at least after the initial turn or winding thereof, has a layer-relationship for example going from the inside layer d on the interior of the helix, radially outward to the next layer e, radially outwardly to the next layer f, and the like. The number of layers is limited solely by practicality, as to the number of tapes employed in the process of this invention to produce the helical, laminated and stepped tape. Although the steps are preferably in the same direction, they may be in opposite directions.

At least after the initial turn of the helicoid tape of FIG. I, strip e is subsequently contacted with about half the width the outside face of the prior turn of strip d, and about one-half of the width of strip e is superimposed and laminated in a parallel alignment on about one-half of the width of the outermost face to strip d of the same turn. Similarly strip f is subsequently fed into contact with the remaining exposed face of the prior turns strip e and with about one-half of the width off is superimposed on and laminated to about one-half of the width of strip 2 of the same turn i.e. the turn being presently produced) on which strip f also is in a parallel alignment. Thereby a laminated-stepped tape results, as produced from typically three separate strips of tape, with a step from about half the width of d up to the top exposed surface of e for about half the surface of e, and thereafter up to the top surface off for the entire (for the FIG. I embodiment) surface off, which remains fully exposed unless additional steps be added on top of f tape in a like manner.

The mandrel his wrapped from top to bottom in FIG. 1 (A) and in a preferred embodiment is a revolvable mandrel. Also in a preferred embodiment, the three separate feed means for the three separate tapes are commonly mounted on a base which may be either manually or automatically moved at a predetermined rate in a direction parallel to the axis of the mandrel whereby the feeding means for the three or more tapes may be moved in a direction (top to bottom in FIG. I (A)) whereby the tape is continually wrapped into additional coils on the portion of a mandrel not yet covered. The angle w represents the necessary angle between the alignment of strip d and the axis of the mandrel h, this angle being predetermined on the basis of the particular diameter of the specific mandrel being employed and also dependent upon the width of the tape d. As strip d width increases, angle w decreases. The rate at which the feeding means must move parallel with the axis of the mandrel in a direction toward the exposed end of the mandrel must be relative to the rate of rotation either of the mandrel itself or the rate of rotation of the feeding means around a stationary mandrel. The angle i is necessarily slightly greater than Zero and much less than as a result of the addition of the thickness of tape d on opposite sides of the mandrel in addition also to the diameter of the mandrel itself, thereby l requiring either a different angle of feed for a tape of substantially identical width for tapes d and e, or (2) alternatively requiring a greater width for tape 2 than tape d. Similarly, angle k is necessarily also slightly greater than zero and possibly greater than angle i, or alternatively f is of greater width. The total of the degrees of angle w, plus the degrees of angle i, plus the degrees of angle k, is less than 90 this being necessary if the coils are to form a helical relationship, as opposed to merely coils being superimposed entirely over one another to produce a roll. A powder box x feeds an appropriate powder onto the exposed surface of each of tapes d and e prior to the wrapping of an additional coil adjacent thereto. Although it is necessary that the exposed areas of d and e be coated, it is immaterial and permissible for also the entire exposed surface of the outer tape, such as in this embodiment the entire outer surface of tape f, to be coated with the powder. Although in this embodiment the powder box x is effectively employed at this point in position in the process and apparatus in a manner whereby the powder is applied after the tapes have been overlapped about half the width of the overlapping tape, it is within the scope of the invention to apply the powder prior to this point. However, this embodiment of the invention of applying the dust at this particular point is a preferred embodiment since it eliminates the possibility of neutralizing or overcoming the tackiness of that portion of the tape where tackiness is still desired for purposes of adhering to a superimposed tape to be overlapped thereon and laminated thereto; by dusting after the tape to be superimposed has been superimposed and overlapped, the possibility of interfering with a subsequent bond between the superimposed and the overlapped tape is thereby avoided. The dust box x similarly must move axially in the direction of wrapping the exposed mandrel at the same rate at which the feeding means relatively move axially in relation to the mandrel around which the plurality of strips are being wrapped.

The FIG. I (B), is a view from the left of the view illustrated in FIG. I (A), the view of (B) more clearly illustrating the combined guide and a roller means for stabilizing the direction of feed of each respective tape as well as predetermining the relative elevation of each feed tape whereby tape d first contacts a mandrel, and subsequently tape e is guided over the top of the outer face of tape d, and similarly tape f is subsequently guided to the mandrel above the outer face of tape e (l) as each respective tape is wrapped upon the mandrel, (2) as e overlaps d, and (3) asfoverlaps e. The view ofl (C) is a side view as FIG. I (A) would be seen from the bottom of FIG. (A), the relative angles of feed of tapes d, e, and f, respectively, over rolls a, b, and 0, respectively, being further emphasized by the particular emphasis in I (C) on the guiding angle at which each respective guide is mounted.

It should be understood that for each of the Figures of I (A), I (B), and I (C), the Figures are only diagrammatically illustrative and do not show all of the customary and conventional, supporting structures for each of the illustrative means of this invention.

The FIGS. II (A), II (B), and II (C), correspond substantially to the views of FIG. I, except that the illustrations of FIG. II illustrates an embodiment in which initially the two or more strips d, e and f are fed optionally over tensioning means g through its respective guides r, s, or t, which regulates the degree of elevation of tape e above tape 11 and the degree of elevation of tape f above tape e and guide the respective tape to the next respective guides m, n, or p, each of which for its respective tape guides the tape at the predetermined desired angle, whereby the respective strips approximately identical widths intersect at an angle such that when in contact with the mandrel the tapes will be wrapped in an overlapping relationship in which the overlapped portions are in substantially parallel alignment with the overlapped tape.

In the embodiment of the type illustrated in II, it is within the scope of this invention to employ a single tape with appropriate blades or cutting means employed at designated points to split a single tape into multiple strips of desired but substantially identical widths in order to feed several strips resulting from the splitting of the original tape through the guide means of the type of FIG. II. For example, reference may be made to U.S. Pat. No. 2,262,636 in which cutting means are employed to sever the width of the tape into several resulting individual strips of about the same widths, subsequently wrapped on the mandrel. A similar type of device could be readily employed in this invention in order to obtain the necessary two or more strips for producing the laminated and stepped tape of this invention.

FIG. III is basically similar to the embodiment illustrated in FIG. II, except that the separate rolls r, s, and t of II are illustrated in III as rolls r, s, and t in a position whereby the feed tapes fed therethrough are positioned in an overlapping relationship prior to the separate tapes being fed to the second guides (not shown) corresponding to the guides of FIG. II designated m, n, and p. The view of III is from the back of the feeding apparatus, facing the mandrel, the overlapping relationship of rolls r, s and I being apparent in this view. However, the overlap of these guides must be less than the overlap of the strips when laminated because angles i and k must each be greater than zero.

FIG. IV typically illustrates the appearance of a helical laminated-stepped tape as viewed typically from the bottom of FIG. I (A), produced by the process and apparatus of this invention; however, it should be noted that in each of the illustrations of I and II, the tapes being fed were fed under the mandrel around and over the top; in the embodiment illustrated in IV (A), such a tape having the helical spiral running in this direction would be formed by either (1) feeding the tape underneath the mandrel as illustrated in FIGS. I and II but overlapping in an opposite direction and moving the axis of the mandrel or alternatively the apparatus upon which the feeding means of the several strips are mounted in the opposite direction from the illustrated in those Figures, or (2) by beginning the wrapping of the mandrel by passing the tapes over the top of the mandrel and then downwardly around and underneath, as in FIGS. I and 11.

Accordingly, for the embodiment illustrated in FIG. IV (B), a laminated-stepped tape as produced from embodiments of either I or II, is illustrated, the direction of steps being the same, but the helix spiraling in the opposite direction as compared to the direction of steps illustrated in IV (A).

FIGS. IV (C) illustrates a typical cross section of the helically wound tape as it would appear when snugly mounted in abutting relationship with the various steps when wound around either a mandrel of the type illustrated in any of FIGS. I, II, or III, or alternatively when wound around a pipe, tube, wire, or the like. In this embodiment the separate steps of the tape d, e, and f are illustrated, and the means on which the tape is helically mounted is designated as 2.

For a more thorough understanding of the necessary relationships between the width of the inner tapes as compared to superimposed outer tapes, the relationship of diameter of the mandrel, and thickness of the respective tapes, and the like, reference is made to U.S. Pat. No. 2,558,849 in which these relationships are typically established and discussed, for example in column 10, lines 67 through column I 1, line I 1. However, additionally reference is made to U.S. Pats. No. 2,046,138, No. 2,637,674, and No. 2,713,383, in which such relationships necessarily also were predetermined in order to establish the illustrated laminated solid" tubules formed in those patents. It should be noted that in each of these patents referred to above, there is no suggestion of the formation of, nor of any possible process that could be employed for the preparation of a coilable, uncoilable, and recoilable helical laminated and stepped tape of this invention. These patents are referred to merely as typical prior art disclosing representative methods that may be employed as one or more of the prior art techniques of accomplishing particular steps of the applicants novel process, and also for the apparatus and tape of this invention.

In the process of this invention of the type described above, as is readily apparent from the above description, it is preferred to feed from appropriate feeding means a first fibrous strip such as d impregnated with an adhesive composition such as either rubber or silicone composition, for example, through at least a first guide means, such as m, and from the guide onto a surface of a mandrel means and helically around a mandrel means, the strip extending from said guide to the mandrel means at an acute angle with an axis concentric to the mandrel means, sufficiently large to form a helical coil having adjacent coils not overlapped, feeding from the feeding means at least the second adhesive composition-impregnated fibrous strip, such as e, of similar or dissimilar adhesive composition, through a second guide means (comprising at least one guide), such as r, at preferably a different level (elevation), for example as illustrated by angle x than the first guide, and the level of the second guide being such that the second strip feeds onto and helically around the beginning coil of the first strip at a second acute angle x sufficiently great that the second helical and overlapping strip is substantially parallel to the first helical strip in alignment, moving at least one of said feeding means and said mandrel means, relative to the other, in a direction whereby the first strip is fed axially onto the uncovered areas of the mandrel means and revolving at least one of said mandrel means or said feeding means around said mandrel means whereby the second strip becomes wound around the mandrel means becomes in the next adjacent subsequently formed coil, wound around the first strip of the first wrapped coil, in an overlapping relationship of the type described above. Similarly, a third strip such as f would be fed at elevation for feeding f after the point of contact of strip d, the latter elevation typically being represented by angle y, occluded between strip e and f. Accordingly, by such a typical process, a helical tape having steps overlapping lower steps of adjacent coils is formed, whereby such a tape when snugly wrapped in an abutted relationship of the edges of the various steps provides a high level of heat and fire protection to the cylindrical object wrapped therein, provided that the composition of the individual strips from which the laminate is produced, is relatively heat and/ or fire resistant.

As discussed above, such a tape may be easily unwrapped in order to allow inspection of the object being protected, and thereafter the helical tape easily again wrapped in the original firm and protective position. The adhesive composition, as stated above, may be any suitable adhesive but preferably is an elastomer composition such as for example is disclosed in the copending application Ser. No. 701,424, commonly assigned, which disclosure in its entirety is hereby incorporated by reference, a preferred elastomer of my invention being an ethylene-propylene rubber composition as the innermost face of the innermost strip of the helical coil of this invention, and the remaining elastomer composition comprising substantially a polychloroprene rubber. The preferred silicones of my invention already have been stated above.

A novel helical laminate-stepped silicone tape of this invention may be defined as at least two strips of material bonded in a stepped relationship providing a staggered and tiered arrangement, and having coil diameter ranging up to about 0.5 inch, in which at least one strip is silicone coated, uncoilable and recoilable as a result of the edges of adjacent coils having been cured in a manner whereby the edges of adjacent coils were not substantially bonded to one another. More particularly, such an uncoilable helical tape includes two or more strips of material overlapping each other along a longitudinal edge to provide a staggered and tiered arrangement, the strips being bonded to each other to form a unified laminate, the strips being coiled in a helicoid construction, in a given length of covering materialthere being more of a length of one strip or alternatively a greater width of said strip as compared to the length of an adjacent joined overlapped strip, adjacent helicoid portions of adjacent coils of individual strips of said tape being substantially in a butt-joint relationship with each other, and portions of overlapping and overlapped strips of the tape being in a ship-lapped joint with respect to each other.

A particular utility of the tape of this invention is that a helicoid flexible covering of a tape according to the above description, provides heat and flame protection for a wire or conduit to be covered, the covering including typically a plurality of the strips comprising substantially asbestos fibrous cloth, a silicone bonding agent, for example, impregnated into and covering the strips, the strips being in a staggered configuration with the edge of at least one strip being offset from the edge of at least one other strip, and the staggered configuration being cured into a helicoid, integral laminated structure, having ship-lapped joints between adjacent and separable coils, the laminated structure being capable of being repeatedly coilable without any substantial bonding together consecutive superimposed coils of the laminated structure and uncoilable whereby the insulation wrap may be repeatedly installed by coiling and removed by uncoiling from a tubular conduit, for example, without damage to either the conduit or the covering itself. In one preferred embodiment of this invention, the silicone material comprises dimethylpolysiloxane including vinyl substituents. In another preferred embodiment, the silicone material comprises a dimethylpolysiloxane including phenyl substituents. in another preferred embodiment the helical flexible covering is formed of three or more strips of about equal width substantially, of asbestos cloth, the inner strip being offset in either direction from the central strip, but preferably the outer strip being offset from the opposite edge of the central strip relative to the inside strip.

The apparatus typically of the type that can be adapted to the process of this invention is an apparatus of the type for producing a solid helicoid laminate of fused coils of overlapping, superimposed strips of material, one strip superimposed on another strip and having overlapping and abutting edges of adjacent coils, and the apparatus including a feeding means for a plurality of at least two strips of the material, adapted to feed strips into a mandrel to produce the laminate, and a plurality of guide means comprising preferably at least two guides per strip, there being at least one guide per strip, said guides having an alignment whereby said strips of predetermined thickness and width are feedable, at acute angles to each others direction of feed and to the mandrels axis, to intersect and overlap in a substantially parallel and overlapping alignment, where the improvement primarily comprises a means for treating at least remaining exposed areas of llli identical widths, sufficiently to substantially overcome, i.e., counteract, or neutralize, any existing tackiness on the remaining exposed areas of the outer face of each overlapped strip, whereby adjacent coils of the laminate when cured result in substantially unbonded overlapping turns of a continuous stepped and tiered laminate of uncoilable and recoilable helical tape.

In the practice of the process of this invention, as is conventional in the application of tacky tapes to a mandrel, in order to prevent the tape from adhering to the mandrel, it is necessary to treat the surface of the mandrel or the surface of the contacting side of the tape with a suitable release composition, such as for example a soap material whereby after the wrapping and curing operation, the cured tape may be removed easily from the mandrel without any substantial amount of sticking of the tape to the mandrel. Other conventional suitable parting agents may be used, such as combinations of stearic acid and silicones, for reducing possible adherence of strips to the mandrel. Various parting agents will be readily apparent to those skilled in the art and will therefore not be described. However, typically film forming type polyvinyl alcohol provides an excellent release agent. The polyvinyl alcohol cures almost instantaneously upon heating the mandrel, peels away from the finished article, and is water soluble for facile removal of any residue. A layer of polyvinyl alcohol may be therefore provided upon the mandrel, the same being very thin, usually less than a thousandth of an inch thick. A paste wax, applied by a cloth might also be used.

The following examples and tables are intended to serve only as illustrative embodiments, and are not intended to unduly limit the scope of the invention except to the extent expressly stated and to the extent that the appended claims are limited. All percentages are by weight unless otherwise stated.

EXAMPLE To a predyed cloth, a silicone rubber dispersion was applied by employment of a Divine coater. In the coating operations the temperature normally ranges from about 150 to about 220 F., normally about l80 F. The cloth was not permitted to remain in the tower for prolonged periods of time. The asbestos cloth so treated was thereby uniformly coated on both sides to from about 56 to about 64 percent by weight of the treated cloth. About five passes were required to achieve this. After the last pass of the asbestos cloth through the Divine coater, the coated cloth was wound-up on a take-off roll with embossed polyethylene liner as wrinkle-free as possible and consistent with existing standard conventional practice. Thereafter the uncured silicone coated asbestos cloth was slit lengthwise into strips of substantially identical widths of three-fourths inch wide or one inch wide in accordance with the particular tapes desired in laminate form. The strips of tape with polyethylene liner intact were wound on a suitable core and the ends thereof stapled to prevent unwinding. Three tapes were placed into holders of a special triple pipe wrapping lathe. The particular lathe employed, after initial setup and adjustment of the relative directions of feed of the individual strips and after elevation of the individual strips, systematically wrapped the mandrel with three tapes in about one-half overlap and mica dusted the laminate area required. Typically the overall apparatus consisted of a vari-drive lathe with an manual or automatic feed carriage on the lathe bed, predetermined to move at the desirable rate of speed. A swivel type horizontal table was mounted on the carriage with two upright posts afiixed thereon; various angles were obtainable on the upright posts relative to the mandrel held between the head and tail piece merely by using the swivel and securing it at a desired angle. To the face of the upright posts on the mandrel side were attached tape slot guides which also were adjustable to various individual angles relative to each other and were adjustable for horizontal movement for adjustment of tape to overlap as required. The strips of tape were fed each overlapped strip of the laminate of strips of substantially through the slot guides and tensioned as required for desirable operation, by use of static tensioning bars, or other equivalent tensioning means. Mica dusting on the tape sections required was accomplished typically by a dust box attached to the frame which followed the manually or automatically moved carriage down the lathe bed while applying the tapes to the mandrel.

After setting up slot guides to lathe and adjusting to size requirement, the mandrel was installed into the lathe head and tail stock. After setting up the mandrel, the mandrel was brush coated with typically a percent solution of AQUAREX" WAQ (trademark) in isopropyl alcohol. The three silicone strips of tape were then pulled through the slot guides with the carriage in position at the lathe head, and the silicone strips were pinned to the mandrel near the lathe head. The lathe was started and typically manually cranked to move the carriage over the lathe bed while visually tracking the tapes into orientation and maintaining a steady feed of the carriage. After wrapping the mandrel, the silicone strips of tape were cut in front of the slot guides, and the ends of the strips of the now laminated tapes were clamped to the end of the mandrel. It was found preferable to overwrap the silicone covering tightly with a suitable heat resistant inert tape such as MYLAR" (trademark) tape using pressure-sensitive tape or other suitable means to hold the MYLAR in place at the ends. The MYLAR tape was applied as wrinkle free as possible and normally with an overlap of about one-fourth to one-half of the width of the MYLAR tape. Thereafter the mandrel wrapped material was vulcanized in a circulating air oven for about 1 hour at about 350, although the time could range anywhere from about 5 minutes up to about 2 hours at temperatures ranging normally from about 300 to 375, for example, although these times and temperatures are not especially critical. However, for preferred results, ranges within these limits would be employed. The vulcanized tape and mandrel on which it was wrapped was removed from the oven at the end of the necessary period of time, and cooled to about room temperature. The MYLAR" film wrapping was removed and discarded and the cured laminated and stepped tape was removed from the mandrel by a twisting motion the entire length of the mandrel and then removed by a generally sliding motion. Thereafter each end of the tape was trimmed as desired, to length requirements.

Following the procedure of the above Example, a series of tapes were prepared by the process and apparatus of this invention. The tapes prepared thereby fulfilled the objects of this invention.

In the above disclosure, the term coated is used interchangeably with the term impreganted."

This invention is not limited merely to the particular elastomers and rubbers specifically referred to, but includes all conventional silicones and rubber elastomers known by the ordinary artisan to be an equivalent or reasonable substitute for those specifically disclosed herein. Typical available literature on silicones includes the General Electric Silicone Rubber HandbookRHB-3, Compounding." Also, the process and apparatus may be employed for making paper or other types of synthetic tapes of the general structure described in the above disclosure, employing any conventional or obvious substitute adhesive in the place of the preferred elastomer composition for this invention discussed at length above. Accordingly, this invention includes all modifications and substitutes of steps and components, for example, which to a person skilled in this field would be obvious.

What I claim is:

l. A process of forming an uncoilable and recoilable heat insulating sleeve for use about a conduit comprising:

helically wrapping a plurality of adhesive-treated elongate flat strips of heat resistant material onto a mandrel in generally parallel superimposed stepped relationship whereby overlying strips cover the joint between underlying strips,

applying to outwardly exposed surfaces of said strips just after they have been wrapped onto the mandrel but rim to subsequent wraps a composition substan rally neutralizing tackiness to the adhesive which it contacts,

curing the adhesive and removing the sleeve from the mandrel so that said elongate strips are adhered together in stepped relationship in a helical formation having a tendency for generally returning to that formation but with substantially no adherence between surfaces of adjacent turns of strips where neutralizing composition was applied whereby said strips as a body may be uncoiled and recoiled to form said sleeve.

2. The method according to claim 1 wherein strips of equal width are helically wrapped onto the mandrel.

3. The method according to claim 1 wherein said adhesive comprised an elastomer.

4. The method according to claim 3 wherein said elastomer is selected from the group consisting of ethylene-propylene rubber and polychloroprene rubber.

UNITED STATES PATENT OFFICE CERTIFICATE 0F COECTTN Patent No. 3,657 4 Dated March 18R 1972 Invent0r(s) Harold J.. Reynolds, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 56, after "strip'being offset" insert w to one side of the central strip and the outer strip being offset Signed and sealed this 27th day of February 1973.

(SEAL Attest:

EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents FORM (10-59) USCOMM-DC 60376-P69 t U-S. GOVERNMENT PRINTING OFFICE I 959 0-366-334, 

2. The method according to claim 1 wherein strips of equal width are helically wrapped onto the mandrel.
 3. The method according to claim 1 wherein said adhesive comprised an elastomer.
 4. The method according to claim 3 wherein said elastomer is selected from the group consisting of ethylene-propylene rubber and polychloroprene rubber. 